The present invention relates generally to reinforced composite structures of high mechanical strength, and more particularly, to reinforced composite tubular bodies suitable for conducting gases, liquids, slurries, solid particulates and the like in diverse industrial applications.
Various types of strip-reinforced composite structures are known in the art. U.S. Pat. No. 3,790,438 to Lewis and Nielsen, for example, discloses a composite formed of a polymeric material reinforced by metallic strips disposed in superposed layers with the strips of each layer overlapping the strips of an adjacent layer by at least a minimum distance referred to as the `overlap width`. The overlap width is chosen to ensure transfer of loads from the polymeric material to the strips. This construction makes it possible to realize reinforced composites of high strength.
However, as described in U.S. Pat. No. 3,790,438, this type reinforced composite can be made using only polymer materials whose coefficient of elongation at breaking (rupture) is greater than 25%. Although the patent itself does not explain why the composite must be limited to polymer materials having a coefficient of elongation at breaking greater than 25%, one of the patentees, Nielsen, in a text entitled "Mechanical Properties of Polymers and Composites", published by Marcel Dekker Inc. of New York (1974), at Vol. II, page 494, specified this as a condition which must be satisfied in order to obtain high strength, and Nielsen made specific reference in the text to U.S. Pat. No. 3,790,438. A second condition mentioned by Nielsen is that the polymeric material must be sufficiently ductile and have a high elongation at rupture so as to decrease the effect of stress concentration due to thermal stresses arising during the manufacturing process. The lower limit of ductility specified by Nielsen for the polymer material has the drawback of excluding use of all high strength thermosetting polymers.